I don't know if you mean after you become eligible for Medicare, but once you start on Medicare, there are a lot of good companies offering Medicare Supplemental (Medigap) insurance and many of them are a lot cheaper than the AARP plan with the same coverage.

It pays to find a good agent or agents who offer plans from different companies so you can find the best fit for you. It's an advantage to compare plan rather than just defaulting to AARP.